NAEP Technical DocumentationSampling of Schools for the 2017 Private School National Writing Assessment

			Computation of Measures of Size School Sample Sizes: Frame and New School

The private school samples were selected with probability proportional to size using systematic sampling from a sorted list. A school's measure of size was a complex function of the school's estimated grade enrollment. At both grades, only one "hit" was allowed per school.

Schools were ordered within each school type using a serpentine sort involving the following variables:

• census region;
• urbanicity classification (based on urban-centric locale);
• race/ethnicity status; and
• estimated grade enrollment.

A systematic sample was then drawn with probability proportional to size using this serpentine-sorted list and the measures of size.

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